The M-Audio O2 follows in the footsteps of the mobile USB MIDI controller that started it all—the Oxygen8. Small enough to fit in a bag along with your laptop, the slim-line M-Audio O2 is perfect for throwing down bass lines, programming drum patterns, triggering effects and tweaking virtual studio parameters—anywhere, anytime. You get 25 full-size, half-action, velocity-sensitive keys, along with eight fully assignable knobs, 8 fully assignable buttons and other real-time control features for performance and programming. One simple USB connection serves as both a MIDI interface and bus power source. Class compliancy with Windows XP and Mac OS X means that you can get down to business without even installing any drivers.